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        검색결과 98

        1.
        2024.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Na4MnV(PO4)3 (NMVP) cathode materials have attracted significant attention as potential candidates for grid applications due to their distinctive structure and high theoretical capacity. However, their inadequate electronic conductivity compromises both cycling stability and rate capability, presenting a challenge for practical implementation. To address this issue, we employed a strategy involving Zr4+ doping and dual-carbon coating to enhance the electrochemical performance of NMVP. The resulting Na3.8MnV0.8Zr0.2( PO4)3/C/rGO composite demonstrated markedly improved rate capability (71.9 mAh g− 1 at 60 °C) and sustained cyclic stability (84.8% retention at 2 C after 1000 cycles), as validated through comprehensive kinetics assessments. The enhanced performance can be attributed to the expanded Na-ion pathways facilitated by large size ion doping and the improved electronic conductivity enabled by the dual-layer coating.
        4,000원
        2.
        2024.07 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Today, the principles of green chemistry are being fundamentally applied in the chemical industry, such as the nitrobenzene industry, which is an essential intermediate for various commercial products. Research on the application of response surface methodology (RSM) to optimize nitrobenzene synthesis was conducted using a sulfated silica (SO4/SiO2) catalyst and batch microwave reactor. The nitrobenzene synthesis process was carried out according to RSM using a central composite design (CCD) design for three independent variables, consisting of sulfuric acid concentration on the silica (%), stirring time (min), and reaction temperature (°C), and the response variable of nitrobenzene yield (%). The results showed that a three-factorial design using the response surface method could determine the optimum conditions for obtaining nitrobenzene products in a batch microwave reactor. The optimum condition for a nitrobenzene yield of 63.38 % can be obtained at a sulfuric acid concentration on the silica of 91.20 %, stirring time of 140.45 min, and reaction temperature of 58.14 °C. From the 20 experiments conducted, the SO4/SiO2 catalyst showed a selectivity of 100 %, which means that this solid acid catalyst can potentially work well in converting benzene to nitrobenzene.
        4,600원
        3.
        2024.07 KCI 등재 구독 인증기관·개인회원 무료
        Energy storage is one of the leading problems being faced globally, due to the population explosion in recent times. The conventional energy sources that are available are on the verge of extinction, hence researchers are keen on developing a storage system that will face the upcoming energy needs. Supercapacitors, also known as ultracapacitors or electrochemical capacitors, are advanced energy storage devices characterised by high power density and rapid charge–discharge cycles. Unlike traditional batteries, supercapacitors store energy through electrostatic separation, offering quick energy release and prolonged operational life. They hold exceptional performance in various applications, from portable electronics to electric vehicles, where their ability to deliver bursts of energy efficiently complements or replaces conventional energy storage solutions. Ongoing research focuses on enhancing energy density and overall efficiency, positioning supercapacitors as pivotal components in the evolving landscape of energy storage technologies. A novel electrode material of NiO/CuO/Co3O4/rGO was synthesized which when used as a supercapacitor, the highest value of CS is 873.14 F/g which is achieved for a current density of 1 A/g under with an energy density of 190 Wh/kg and the highest power density of 2.5 kW/kg along with 87.3% retention after 5000 GCD cycles under 1 M KOH.
        4.
        2024.05 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This review explores the potential of pillared bentonite materials as solid acid catalysts for synthesizing diethyl ether, a promising renewable energy source. Diethyl ether offers numerous environmental benefits over fossil fuels, such as lower emissions of nitrogen oxides (NOx) and carbon oxides (COx) gases and enhanced fuel properties, like high volatility and low flash point. Generally, the synthesis of diethyl ether employs homogeneous acid catalysts, which pose environmental impacts and operational challenges. This review discusses bentonite, a naturally occurring alumina silicate, as a heterogeneous acid catalyst due to its significant cation exchange capacity, porosity, and ability to undergo modifications such as pillarization. Pillarization involves intercalating polyhydroxy cations into the bentonite structure, enhancing surface area, acidity, and thermal stability. Despite the potential advantages, challenges remain in optimizing the yield and selectivity of diethyl ether production using pillared bentonite. The review highlights the need for further research using various metal oxides in the pillarization process to enhance surface properties and acidity characteristics, thereby improving the catalytic performance of bentonite for the synthesis of diethyl ether. This development could lead to more efficient, environmentally friendly synthesis processes, aligning with sustainable energy goals.
        4,300원
        5.
        2024.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cu2+/polyacrylonitrile composite fibers were prepared by electrospinning, and then Cu/carbon nanofibers (denoted as Cu/ CNF-X; X = Cu content, 0, 3, or 5 wt%) were formed by calcining them. The effects of Cu2+ content and carbonization temperature on the conductivity and electrothermal conversion of Cu/CNF-X were investigated. The results revealed that the conductivity and electrothermal properties of Cu/CNF-X improve with the increase in the Cu2+ content and carbonization temperature. When the carbonization temperature was 800, 900, or 1000 °C, the conductivity of Cu/CNF-5 (0.08, 0.68, or 2.48 S/cm, respectively) increased to 1.6, 1.5, or 1.6 times that of Cu/CNF-0, respectively. The highest instantaneous surface temperatures of Cu/CNF-5 calcined at 800, 900, and 1000 °C (36, 145, and 270.2 °C, respectively) increased by 4, 25.5, and 44.6 °C, respectively, compared with those of the corresponding Cu/CNF-0 samples (32, 120.3, and 225.6 °C, respectively). Thus, the addition of a small amount of Cu2+ effectively improved the conductivity and electrothermal conversion performance of Cu/CNF-X, which has potential application value in industrial products in the future.
        4,000원
        7.
        2023.07 구독 인증기관·개인회원 무료
        In this research, given the recent spurt of luxury brands featuring their products in the metaverse, we examine if the use of luxury brand items to enhance one’s virtual avatar augments the gamer’s sense of confidence, empowerment, and actual performance. We conduct two studies to test the same. In our first study, we simulated a gaming environment on an online survey portal and asked participants to choose their avatar features. We provided them with a branded item (luxury/regular). Consequently, we asked them to indicate their level of confidence, and empowerment. They were asked to play a game to record their actual performance. In our second study, we asked participants to choose their avatar on an online game on their mobiles and similarly provided them with a branded item (luxury/regular). We then measured their confidence, and empowerment and observed their actual performance.
        8.
        2023.07 구독 인증기관 무료, 개인회원 유료
        In recent years, social media influencers (SMIs) have brought dramatic shifts to the marketing trend. Apart from product endorsement and ad campaigns, they are increasingly hired by brands for promoting social causes including Black Lives Matter movement, COVID-19, and LGBTQ+ issues owing to their perceived authenticity and expertise (Open Influence, 2022). As such, brands promoting social causes to take ethical obligations to the society, namely, corporate social responsibility (CSR), has become an indispensable business practice (McWilliams & Siegel, 2001). Accordingly, past studies revealed that SMIs’ capability of creating authentic connection with target consumers and the fact that stakeholder awareness and authentic motives are preconditions for the success of CSR initiatives can create a synergic effect (Yang et al., 2021).
        4,000원
        9.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: Germ cells undergo towards male or female pathways to produce spermatozoa or oocyte respectively which is essential for sexual reproduction. Mesenchymal stem cells (MSCs) have the potential of trans-differentiation to the multiple cell lineages. Methods: Herein, rat MSCs were isolated from bone marrow and characterized by their morphological features, expression of MSC surface markers, and in vitro differentiation capability. Results: Thereafter, we induced these cells only by retinoic acid supplementation in MSC medium and, could able to show that bone marrow derived MSCs are capable to trans-differentiate into male germ cell-like cells in vitro. We characterized these cells by morphological changes, the expressions of germ cell specific markers by immunophenotyping and molecular biology tools. Further, we quantified these differentiated cells. Conclusions: This study suggests that only Retinoic acid in culture medium could induce bone marrow MSCs to differentiate germ cell-like cells in vitro . This basic method of germ cell generation might be helpful in the prospective applications of this technology.
        4,000원
        10.
        2022.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Background: In order to improve the daily life of stroke patients, it is necessary to restore walking performance. Improving gait performance is one of the main goals for stroke rehabilitation. Objectives: To investigate the change in gait parameters through evaluation of one stroke patient before, during, and after wearing the weight vest. Design: A case study. Methods: This study is an ABA study design. In principle, one assessment per day (A1) was measured three times without wearing the weight vest. Intervention assessment (B) was performed 6 times while wearing the weight vest. The second baseline evaluation (A2) was measured three times with the weight vest removed again. Results: The gait speed was increased when the weight vest was removed than when the weight vest was worn. Also, gait symmetry increased when wearing the weight vest. Conclusion: Wearing the weight vest can reduce the gait asymmetry in stroke patients and increase the gait speed after wearing the weight vest.
        4,000원
        11.
        2022.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Alzheimer's disease (AD) is one of the most common forms of dementia, affecting more than 50 million people globally. The onset of AD is linked to age, smoking, obesity, hypercholesterolemia, physical inactivity, depression, gender, and genetics of an individual. The accumulation of Aβ peptides and neurofibrillary tangles (NFTs) in the brain is one of the critical factors that lead to AD, which is known to disrupt neuronal signaling and causing neurodegeneration. As per the current understanding, inhibiting the accumulation of Aβ peptides and NFTs is crucial in the management/treatment of AD. Latest research studies show that nanoparticles have the potency of improving drug transport across the blood–brain barrier easily. Specifically, graphene quantum dots (GQDs), a type of semiconducting nanoparticles, have been established as effective inhibitors for blocking the aggregation of Aβ peptides. The small size of GQDs allows them to pass through the blood– brain barrier with ease. Moreover, GQDs have fluorescence properties, which can be used to detect the concentration of Aβ in vivo. In recent years, compared to other carbon materials, the low cytotoxicity and high biocompatibility of GQDs, give them an advantage in the suitability and clinical research for AD. In this manuscript, we have discussed the role of different types of nanoparticles in the transportation of encapsulated or co-assembled compound drugs for the treatment of AD and importantly, the role of GQDs in the diagnosis and management/treatment of AD.
        4,600원
        12.
        2022.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This work using first-principles theory proposed PdN3- doped CNT ( PdN3-CNT) as a potential gas sensor for detection of NO, NO2 and O3 in the air insulated equipment, to evaluate its operation status. Results indicate that the PdN3- CNT behaves chemisorption upon three gas species, with adsorption energy (Ead) of − 2.15, − 1.91 and − 1.96 eV, and charge-transfer (QT) of − 0.141, − 0.325 and − 0.419 e, respectively. The band structure (BS) and density of state (DOS) analysis reveal that the gas adsorptions cause remarkable deformations in the electronic property of the PdN3- CNT, leading to the increase of the bandgap for the gas adsorbed systems and verifying the strong binding force of the bonded atoms from the orbital DOS. Combined with the results by frontier molecular orbital theory, we presume that PdN3- CNT is a promising sensing material to be explored as a resistance-type gas sensor for detection of NOx with higher electrical response upon NO. It is our hope that our theoretical assumption could be further studied and realized in the following experiential research, which would be meaningful to propose novel sensing candidate in the field of electrical engineering to guarantee the safe operation of the air insulation equipment.
        4,000원
        13.
        2021.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The printing process can have to print various colors with a limited capacity of printing facility such as ink containers that are needed cleaning to change color. In each container, cleaning time exists to assign corresponding inks, and it is considered as the setup cost required to reduce the increasing productivity. The existing manual method, which is based on the worker’s experience or intuition, is difficult to respond to the diversification of color requirements, mathematical modeling and algorithms are suggested for efficient scheduling. In this study, we propose a new type of scheduling problem for the printing process. First, we suggest a mathematical model that optimizes the color assignment and scheduling. Although the suggested model guarantees global optimality, it needs a lot of computational time to solve. Thus, we decompose the original problem into sequencing orders and allocating ink problems. An approximate function is used to compute the job scheduling, and local search heuristic based on 2-opt algorithm is suggested for reducing computational time. In order to verify the effectiveness of our method, we compared the algorithms' performance. The results show that the suggested decomposition structure can find acceptable solutions within a reasonable time. Also, we present schematized results for field application.
        4,200원
        14.
        2021.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        This paper presents the characteristics of gentamicin-loaded into cetyl trimethyl ammonium intercalated montmorillonite (GtM/CTMA/Mt) as a hybrid composite for a slow-released antibacterial delivery systems. The work describes the successful immobilization of gentamicin into the interlayers of surfactant-modified montmorillonite. Physicochemical characterization of the material is carried out by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. The kinetics of the gentamicin release is investigated by in vitro study and analyzed based on UV–Vis spectrometry. In addition, antibacterial study is performed towards Klebsiella pneumoniae Staphylococcus aureus, Escherichia coli, and Streptococcus pyogenes. The results show that the gentamicin loading into CTMA/ Mt increases the effectiveness of the antibacterial activity, as shown by the higher inhibition zone for all tested bacteria, compared to gentamicin as a positive control. The kinetics study suggests that the gentamicin release obeys the modified Korsmeyer–Peppas model. The physicochemical study and activity test demonstrate the feasibility of the GtM/CTMA/Mt for practical applications.
        4,000원
        15.
        2020.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Hispidin is a secondary metabolite found in numerous medicinal mushrooms that has attracted significant attention, owing to its distinct biological effects, including antioxidant, anti-inflammatory, antitumor, and cytoprotective properties. Experiments are being carried out to study the interaction of detonation nanodiamonds (DNDs) with synthetic and natural hispidin sourced from extracts of Pholiota sp. fungus. The bioluminescence method is used to determine the adsorption/ desorption properties of DNDs toward hispidin. It is found that hispidin forms strong conjugates with DNDs, and the use of various eluents does not result in a significant release of the adsorbed hispidin molecules. DND-bovine serum albumin (BSA) complex, where DNDs serve as a carrier for the protein and the latter acts as a hispidin sorbent, has been developed and applied in hispidin adsorption/desorption tests. The results support the use of the DNDs as a carrier for hispidin in medical applications. They also advocate the application of the DND-BSA complex for isolating the substance from fungal extracts.
        4,000원
        16.
        2020.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Dishwashing tools such as sponges, scourers, and dishcloths are known to harbor dense and diverse microbial communities, including pathogenic bacteria. In this study, the potential of corona discharge plasma jet (CDPJ) as a disinfectant was tested to improve the hygienic quality of dishwashing tools. For the simulation of microbial contamination, selective pathogenic bacteria (Escherichia coli O157:H7, Staphylococcus aureus, and Pseudomonas putida) were inoculated on selected dishwashing tools (dishcloth, sponge, and scourer) at concentrations of 6.55 to 8.77 log CFU/cm 2 . CDPJ generated at 20 kV voltage and 1.5A current was used for decontamination, whereas a sample-to-electrode distance of 25 mm was maintained during the treatment. Following CDPJ treatment for 5 min, the viable counts of E. coli O157:H7, S. aureus, and P. putida were reduced by 4.30-4.56, 3.71-4.78, and 3.50-3.83 log, respectively. The rates of inactivation were varied among the pathogens, decreasing in the order E. coli O157:H7 > S. aureus > P. putida. Among tested kinetic models, namely log-linear, log-linear with shoulder, and Weibull models, the log-linear with shoulder model was found to be the most suitable model to explain the CDPJ inactivation of the pathogens. In conclusion, CDPJ can be used as a potential sanitizing agent for dishwashing tools.
        4,000원
        17.
        2020.04 구독 인증기관 무료, 개인회원 유료
        홍콩의 비중국어권 학습자의 실용문 학습과 상황에 맞는 정확한 표현 능력의 제고를 위해 홍콩대학 Dr. Mark Shum Shiu Kee (岑紹基) 연구팀은 교육국의 연구비 지원을 받아 2016~ 2017년 비중국어권 학습자용 실용문 교재를 개발하였다. 본 논문은 기능 어법 이론을 바탕으로 비중국어권 학습자용 실용문 교재를 어떻게 설계했는지를 밝히고, 본 교재가 비중국어권 학습자의 기능어 운용 능력 향상에 끼친 영향에 대해 고찰하였다. 또한 연구팀이 개발한 실용문 교재가 비중국어권 학습자의 기능어 운용 능력 향상에 어떠한 성과를 가져왔는지를 밝히는 것을 본 논문의 주목적으로 삼았다. 연구팀은 체계 기능 언어학 이론을 바탕으로 비중국어권 학습자용 실용문 교재를 개발하였으며, 실용문의 종류에 따라 달라지는 의사전달 기능, 도식 구조, 어법 특징을 고려하여 읽기 예문의 주제를 선정하였다. 또한, 비중국어권 학습자가 기능어와 구문 활용에서 갖는 어려움을 실용문 종류에 따라 나누어 분석하였다. 아울러, 「文類功能(문체기능)」 이론 및 「閱讀促進學習(읽기촉진학습)」 교수법을 참고로 읽기 쓰기 통합형 쌍방향 연습법을 개발하여 학습자가 모범 예문을 분석, 해체 및 재구조화를 할 수 있게 하고, 더 나아가 학습자가 스스로 실용문 쓰기를 할 수 있도록 도왔다. 이외에도, 교육 일선에서 지도하고 있는 중국어 교사들을 초청하여 시범적으로 교수법을 시행하고 이를 통해 본 교재의 실제 효과를 검증해 보았다. 학습자가 작성한 실용문을 교수법 시행 전후로 비교 분석하고 교사와 학습자 인터뷰도 함께 진행하여, 본 실용문 교재가 비중국어권 학습자의 기능어 운용과 실용문 쓰기에 끼친 효과를 평가하였다. 아울러, 본 연구 결과를 바탕으로 비중국어권 학습자 실용문 교육을 위한 실행 가능한 몇 가지 방안을 제시하였다.
        8,000원
        19.
        2019.10 구독 인증기관 무료, 개인회원 유료
        중국어의 글자와 단어는 형태·소리·의미상 매우 다양하고 복잡한 특성을 가지고 있다. 이로 인해 많은 중국어를 사용하지 않던 (non-Chinese speaking) 학생들은 이와 같은 중국어의 글자와 단어·구 조합의 다양한 특징을 쉽게 변별하기 어렵다. 모국어인 영어 또는 필리핀어, 파키스탄어, 네팔어 등과 같은 기본 자모를 갖춘 언어들은 모두 병음 문자 계통을 사용 하기 때문에, 중국어에서 사용하는 한자의 자형·자의의 개념에 대한 이해가 부족할 수 밖에 없다. 이로 인해 그들은 한자를 쓸 때마다 매우 큰 어려움을 겪게 된다. 이를 해결하기 위한 방법으로 제시된 『閱讀促進學習』(Reading to Learn, 이하 'R2L'이라고 약칭한다.) 교육법은 그들의 어려움을 극복하는데 일정한 성과가 있었다. 본 논문은 중국어가 비 모국어인 학생들의 대외한어 수업에서 R2L을 사용하여 한자를 가르치는 현장 설계와 그 수업 절차를 관찰 및 분석하였고, 실험 결과 이 교육법이 학생들의 말과 글을 묘사하는 능력을 향상시키는 데 일정한 효과가 있음을 확인하였다. 또한 '사례연구'라는 연구방법으로 R2L 교육법이 중국어를 모국어로 하지 않는 홍콩 학생들의 대외한어 작문 수업에서 어떻게 활용되고 있는지에 대해 연구를 진행하였고, R2L 교육법을 통해 중학교 1학년 학생들에게 문장 또는 글자를 묘사하는 것을 교육하는 현장 상황을 분석하였다. 또한 교사와 학생들의 인터뷰, 수업 심층연구 및 원문분석 등의 연구 도구들을 활용하여 대외한어교육현장에서 진행되 는 한자교육에서의 R2L 교육법 도입과 그 가치(효율성)에 대한 내용을 총정리하였다. 본 연구결과를 통해, 중국어 교사가 R2L교육법을 실시한 후, 서로 다른 수준을 갖고 있는 학생들이 글자와 문장을 묘사하는 능력을 제고시키는 데 효과가 있었음을 확인할 수 있었다. 연구자들은 본 논문의 연구결과를 토대로, 대외한어교육현장에서 R2L교육법을 응용한 한자교육의 전략에 대해 관련된 의견들을 제시하고자 한다.
        7,700원
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